Most mobile devices are configured to receive and operate removable Universal Integrated Circuit Cards (UICCs) that enable the mobile devices to access services provided by wireless service providers, which can include mobile network operators (MNOs) and virtual MNOs (VMNOs). In particular, each UICC includes at least a microprocessor and a read-only memory (ROM), where the ROM is configured to store different applets and authentication data that the mobile device can use to register and access services of the wireless service providers. Typically, a UICC takes the form of a small removable card (e.g., a SIM card) that is configured to store a single MNO profile and to be inserted into a UICC-receiving bay included in the mobile device. In more recent implementations, however, UICCs are being embedded directly into system boards of mobile devices and are configured to store one or more MNO profiles (e.g., electronic SIMs (eSIMs))—e.g., one eSIM (profile) for a local MNO, and another eSIM (profile) for an international MNO. Notably, these embedded UICCs (eUICCs) provide several advantages over traditional, removable UICCs. For example, some eUICCs include a rewritable memory that can facilitate eSIM addition, deletion, and updating for accessing new and/or different services provided by MNOs. EUICCs can also eliminate the necessity of including UICC-receiving bays within mobile devices. The implementation of eUICCs therefore not only increases the flexibility of mobile devices, but also simplifies their design and frees up space for other components.
Despite the foregoing advantages provided by eUICCs, new challenges arise with respect to maintaining backward compatibility with external processing modules designed to work with file systems as installed on and structured for UICCs, while also providing the increased flexibility offered by eUICCs, particularly with eSIM (profile) switching that impacts the file systems installed on eUICCs. Legacy file systems for legacy UICCs can mix MNO specific information with hardware specific (e.g., UICC based) information. File system management for eUICCs, on which eSIM profiles can be added, deleted, and/or modified, can be improved to allow for flexible eSIM profile management as well as retain backward compatibility with external processing modules, e.g., a terminal interface, that are also designed to work with legacy UICCs.